HELP! HJ45 Glow Plug Controller heating too fast (1 Viewer)

[lostmarbles]

... This leads me to the conclusion that there is a leak to ground in the wire between the controller and the busbar.
Disconnect the Black/Yellow stripe wire from the controller and from the busbar.
Run a new (test) wire (same AWG size) from the controller to the busbar. This should eliminate a wire problem.
Let us know how this turns out.
Rudi

...I just got AWG8, unhooked black/yellow, and hooked it up to the busbar/controller.
Looks like a second is shaved off, but I'm still getting it heating up way too fast with no plugs glowing. I measured power coming into the controlled at around 12v and power to the busbar (at the controller connection AND the busbar connection) at a mere 0.7v.

Well this is symptomatic of a dead short (to your engine block) at your busbar.

I don't know about you Athensrep, but I prefer to look at wiring diagrams where I can fully understand at a glance how everything works.

With this in mind, many moons ago I put together a wiring diagram for my 1979 12V BJ40 based on

• the FSM wiring diagrams
• what the factory actually did in practice, and
• how the insides of components are actually wired in practice

So just now I've modified this old diagram to represent how I expect your 1979 12V HJ45 should be:

Note that I've also added (in red) how I understand your momentary switch should be wired.

Hope this helps...

 

[bj40green]

This is un-be-lie-va-ble! This means that you have a short at the busbar.
Last check you can do is: disconnect the test wire from the busbar. There should be 12V at that end of the wire when you hit the button.

Can you post detailed pictures of that busbar?

Rudi

 

[lostmarbles]

..Can you post detailed pictures of that busbar?

Rudi

x2

 

[athensrep]

Guys, I'm sorry. This is ridiculous...but I have a suspicion it's the busbar itself. Was the original unit aluminum?

Unhooked the test wire and checked it. Getting 12v.

I'll upload pics of that bus bar area...

 

[athensrep]

 

[bj40green]

YOU have a short to ground!!!!!
Should look like this one on top in this picture.
The red creation was for measuring purposes.

Release the nuts a bit and move the busbar away from the engine head.
Make sure that the busbar is not touching anything.
Order a new one or make one yourself like I did.

Rudi

 

[RufusTheDufus]

I think he might be missing the nuts that go below the busbar. hard to tell from the photos. My busbar looks just like his but I have to use nuts on top and below the bus bar otherwise cranking down on the top side only will result in shorts to the glow plug case. The plastic insulator around the threaded tip is usually too small to be trusted without a much larger diameter nut on top of it.

 

[athensrep]

Many thanks for the diagram. It's quite helpful.

I made a busbar out of some scrap aluminum I have here which is the same approximate thickness as the worn one that was on the cruiser. Unfortunately, I'm still frying at the same time and pulling 0.7v at the busbar.

Stumped.


I owe you guys some home brewed beer after all this...

 

[RufusTheDufus]

BTW, my H had that exact same busbar.

Can we see a photo of the wire connected to the busbar? I looked here but did not see it.

 

[lostmarbles]

I just looked at 1976 and 1978 H-engine FSMs and they do show a flat straight busbar just like you have there Athensrep:

(I at first thought you should have one looking more like mine.)

So it shouldn't be touching your head, but if it is then that would certainly explain what's happening.

Perhaps you might like to do my trick to get it sitting further away.

I sandwich the busbar at each glow plug between an upturned nut and another normally-orientated nut.

I do this because our old engines were designed for 5mm glow plug terminal thread size and most modern plugs (like those you're using there) have reverted to smaller-diameter 4mm. And I find the double-nuts improve the surface contact area.

In your case, as well as improving the contact area, double-nuts will also put the bus bar further away from the head bolts...

Here's my busbar with double-nuts in use (on my spare engine):

 

[lostmarbles]

BTW, my H had that exact same busbar.

Can we see a photo of the wire connected to the busbar? I looked here but did not see it.

And if there isn't a problem there either, then maybe we do have a rogue glow plug that represents a dead short

 

[RufusTheDufus]

I sandwich the busbar at each glow plug between an upturned nut and another normally-orientated nut.

I do this because our old engines were designed for 5mm glow plug terminal thread size and most modern plugs (like those you're using there) have reverted to smaller-diameter 4mm. And I find the double-nuts improve the surface contact area.

In your case, as well as improving the contact area, double-nuts will also put the bus bar further away from the head bolts...

Same setup I use because I did have a problem in the past with poor contact on that H engine. The busbar is made of some soft material that distorts too easily if there's not a similarly-sized clamping surface below the nut on the top side.

 

[RufusTheDufus]

It should be easy enough to check for continuity between the bus bar and the cylinder head. Then it's just a matter of disconnecting the busbar one glow plug at a time until the short goes away.

 

[bj40green]

It should be easy enough to check for continuity between the bus bar and the cylinder head. Then it's just a matter of disconnecting the busbar one glow plug at a time until the short goes away.

Those 8.5V glow plugs are 0.85 ohm each, times 6 in parallel is about 0.15 ohm.
You'll need an ohm meter with 2 digits behind the dot to see the difference between 6 functional plugs (0.15 ohm) and a short to ground (0.00 ohm).

Rudi

 

[athensrep]

To recap -
- new 8.5v NGK plugs
- hj47 enclosed type controller
- test wire from controller to busbar
- impromptu busbar cut from aluminum
- getting .7v at the busbar when momentary switch it depressed (same reading with new and old busbar)
- getting 12v to controller
- doubled up on nuts (nuts under busbar to help contact)

I'm getting .7v at the busbar so I unhooked one terminal after another and checked along the way...

- disconnect busbar at furthest plug and took reading - .8v
- second disconnected - .96v
- third- 1.24v
- fourth -2.1v
- fifth - 3.2v
- sixth glow plug connected directly to test wire - 4v initially climbing to 7v after 10 seconds. Controller is Oven hot at 10 seconds with one plug connected.

Is the ground on my block toast?

 

[RufusTheDufus]

- sixth glow plug connected directly to test wire - 4v initially climbing to 7v after 10 seconds. Controller is Oven hot at 10 seconds with one plug connected.

Is the ground on my block toast?

Could you try each of the other five plugs in the same position and run the same measurements? The

If your block ground was toast I'd expect the voltage readings to be much higher because there would be more resistance between the plugs and the negative battery terminal.

Do you have any means of measuring current like a clamp-on meter? It would be helpful to know how much current is causing your glow controller to light up.

When you say you are getting 12v to the controller when are you taking this measurement? With the momentary switch activated or off?

 

[athensrep]

I'll test each individual plug with the test wire from the controller.

I don't have a clamp on meter. Just a multi right now.

I'm getting 12v to the controller only when it's activated. I get 12v out to the busbar from the controller (when it's not connected to the plugs/busbar). When I do connect the busbar to the controller wire, I'm getting a constant .7v when momentary switch is activated.

 

[athensrep]

OK - Just tested each individual plug from the controller. Each one measures out at 4v initially (and climbs to around 7v when you hold the momentary switch).

 

[bj40green]

Rufus may have a point.
How much DC Amps can your multi meter handle?

 

[athensrep]

Rufus may have a point.
How much DC Amps can your multi meter handle?